Patent Literature 1 discloses that a wire bonding apparatus provided with an inversion unit enables to perform bonding onto a substrate having an area wider than the bonding area of the wire bonding apparatus. Specifically, when an XY coordinate system is set at the center of the substrate, bonding is performed while sliding the substrate in the X direction in the first quadrant and second quadrant on the far side, and then bonding is performed while sliding the substrate in the X direction in the third quadrant and fourth quadrant which have come to the far side after inverting the substrate. This enables to perform bonding onto a substrate having an area wider than the bonding area of the wire bonding apparatus.
In the above-described wire bonding apparatus, when a substrate is detached from the bonding stage and displaced to the inversion unit for inversion, the temperature of the substrate will decrease during this displacement period, and therefore re-preheating is needed for bonding in the third quadrant and the fourth quadrant after inversion. As the result, the productivity may decrease and a risk of cracking in the substrate will also increase.
Moreover, in the above-described wire bonding apparatus, when a substrate is exchanged by another substrate having a different thickness and bonding is attempted to be performed onto the latter, an operator always adjusts the apparatus so as to match the height of the substrate, and therefore it takes time to exchange product types and so on.
Patent Literature 2 discloses that a wire bonding apparatus provide with a rotation drive mechanism for rotating a bonding stage enables to perform bonding onto a substrate having an area wider than the bonding area of the wire bonding apparatus. Specifically, when an XY coordinate system is set at the center of the substrate, bonding is performed in the first quadrant and the second quadrant on the far side while expanding a movable range with an XY table having a bonding head mounted thereon, and then bonding is performed in the third quadrant and the fourth quadrant which have come to the far side after rotation by 180°. This enables to perform bonding onto a substrate having an area wider than the bonding area of a wire bonding apparatus.
In the above-described wire bonding apparatus, because the weight of the bonding stage itself is heavy, if this heavy bonding stage is rotated by the rotation drive mechanism, the stiffness of the bonding stage will decrease, and accordingly it is difficult to reliably stop the bonding stage. Moreover, vibration is likely to occur in the bonding stage during the bonding process. Thus, in the above-described wire bonding apparatus, it is difficult to accurately position the bonding stage, and accordingly an increase in the bonding speed is difficult to achieve and fine-pitch bonding also is difficult.
Patent Literature 3 discloses that a brake unit with an electromagnet is provided at the rotary shaft of a wire bonding apparatus. Here, once a column is stopped at a predetermined rotation position, then a control circuit energizes the electromagnet so as to be attracted to a disk, thereby fixing the rotary shaft.
In the above-described wire bonding apparatus, because a magnetic force by the electromagnet is used, this magnetic force may adversely affect a semiconductor element and the like inside an object to be bonded.